Trays of the general type involved herein are known from U.S. Pat. Nos. 2,767,532 and 3,270,877. In said patents, the trays are made of paper. Experience with such paper trays has created substantial problems in connection with packaging of ampoules or the like. The paper trays are extremely sensitive to moisture in the atmosphere. When the atmosphere is humid, the trays have little or no strength and frequently cause jam ups in packaging equipment. The present invention is directed to a tray which eliminates such problems and has other desirable features.